In modern day boring bar applications higher and higher speeds are achieved. At whatever levels, however, each application must be evaluated in terms of a wide range of variables, and in terms of the increasing demand for precision tooling.
In developing boring bar equipment it is desirable to provide rapid adjustment of indexable inserts without sacrificing accuracy due to traverse bar loading. With respect to boring bar equipment, which include the use of adjustable cartridges coupled to the bar, it is desirable that design improvements include a cartridge which is economical to manufacture, easy to use and one which will accommodate existing cutting inserts. To achieve the desired accuracy in machining it has been found necessary to adjust for the manufacturing tolerances of the cutting insert and cartridge to which it is affixed. Without being bound by a theory of operation, it is believed that some means of adjustment is necessary because the stacking of manufacturing tolerances between the boring bar, cartridge, and insert cannot be compensated for using fixed pocket designs. Cartridge designs affixed to the periphery of a boring bar by screws, clamps, or wedges, and which focus on the tolerance problem by affording adjustment, either are excessively massive, resulting in moment arms destructive to high speed boring bars, or communicate the adjustment force to the bar creating bowing conditions. It is desirable to alleviate these problems by providing an improved adjustable cartridge.
Cartridges which provide adjustment for cutting inserts are known. For example, U.S. Pat. No. 3,885,282 to Pataky describes a machining tool including a holder and insert to which a cutting tool can be attached. The insert is rotatably mounted in a recess in the holder and fixed in a desired position relative to the holder by a locking screw. Rotatable adjustment of the insert allows for the altering of the tip working angle. In U.S. Pat. No. 4,631,994 to Jester et al, a linearly and angularly adjustable holder for a cutting tool is provided. Such tool permits pivotal adjustment by means of an adjustment screw having a threaded portion seated in a basic element and a head which engages a recess in a rotatably mounted receptacle element which holds a cutting tool insert. Rotation of the adjustment screw causes rotation of the receptacle element. However, the structure described in these patents is not directed to alleviating the problem of "stacked" tolerances as described herein. In addition, high speed boring bars cannot meet the precision cutting parameters required today with traditional cartridges mounted to the periphery of the boring bar due to the chatter created. Although creating a recess large enough to seat the cartridge within the bar may stablize the bar, radial adjustment where the adjustment force is directed against the bar would still induce bowing in narrow diameter boring bars. It is therefore desirable to provide an adjustable insert cartridge recessed within a boring bar where the force required for radial adjustment of the insert is insufficient to induce bowing in narrow bars. It is further desirable to provide an adjustable cartridge which is properly balanced particularly in high speed applications. None of the prior art deals with these considerations.